The invention relates in general to the use of high resolution microscopy for integrated circuit (IC) specimen probe stations, and particularly to methods and system for probing with electrical test signals on integrated circuit specimens using a scanning electron microscope (SEM) positioned for observing the surface indicia of the specimen identifying the electrically conductive terminals for the positioning of the probes.
Presently, probe stations typically employ optical microscopes. Although the diameters of wafers are getting larger, the structures constructed on and in those wafers are getting smaller. In the past several decades, the industry has driven the size of these structures from large sizes on the order of hundredths of an inch to small fractions of micrometers today. Until recently, most structures could be observed by normal high magnification light microscopes and probed. However, modern structures have now achieved a size that no longer allows viewing with standard light microscopes. With the industry integrated circuit design rules driving towards 0.18 micron features and smaller, most advanced optical light microscopes cannot be relied upon to accurately identify the electrically conductive terminals from the conductive path indicia of the surface of the integrated circuit specimens under test. Additionally, when viewing very small features on a specimen, the optical microscope lens often must be positioned so close to the specimen that it may interfere with the test probes.
Another approach is necessary in addition to optical microscopy if the industry is to continue to probe these structures, which is surely needed. It would be desirable therefore to provide a probe station which can visualize and probe features not typically visible under even the most advanced light microscope, that can be used in conjunction with electron optics while maintaining the features typically found on optical microscope probe stations.
It is an object of the present invention to provide probing with high resolution analytical probe stations which overcome the disadvantages and problems of the prior art.
It is another object of the invention to provide high resolution probe station methods and system for applying electrical test signals to an integrated circuit specimen.
It is further object of the invention to provide probing for positioning electrical test signals on an integrated circuit specimen using a scanning electron microscope for observing a surface of the specimen.
It is yet another object of the invention to provide a vacuum chamber in which electrical signals from a computer are coupled to motorized manipulators and a plurality of probes allowing the computer to communicate with the motorized manipulator for positioning the probes for applying electrical test signals.
Briefly summarized, the present invention relates to a method and system for probing with electrical test signals on an integrated circuit specimen using a scanning electron microscope (SEM) or a Focus Ion Beam (FIB) system positioned for observing a surface of the specimen exposing electrically conductive terminals on the specimen. A carrier is provided for supporting the specimen in relation to the scanning electron microscope while a computer acquires an image identifying conductive path indicia of the surface of the specimen from the scanning-electron microscope. A motorized manipulator remotely controlled by the computer, or directly by the operator using a joystick or the like, may manipulate a plurality of probes positionable on the surface of the specimen for conveying electrical test signals inside a vacuum chamber inner enclosure which houses the scanning electron microscope, the carrier, the motorized manipulator and the plurality of probes for analyzing the specimen in a vacuum. A feedthrough on the vacuum chamber couples electrical signals from the computer to the motorized manipulator and the plurality of probes. The computer communicates with the motorized manipulator for positioning the plurality of probes, and for applying electrical test signals to the terminals on the specimen using the image acquired by the computer to identify the electrically conductive terminals from the conductive path indicia of the surface of the specimen observed with the scanning electron microscope.
Other objects and advantages of the present invention will become apparent to one of ordinary skill in the art, upon a perusal of the following specification and claims in light of the accompanying drawings.